Samsung SF4500, Service Manual

Page: 43 / 130

6-12 Samsung Electronics
6-1-4-4. IMAGE PROCESSING
1) Image signal input: CIS output signals are offset at
1-4V with about 2.8V white level. Optimum input
level of SCANIP is 1.5V offset and 3.5V white
level. So OPA M P is used to design
interface circuit of SCANIP.
2) Image processing : The scanner reads pixel data
value of image sensor CIS(Contact Image Sensor)
300dpi lines by 300dpi lines, and stores it in scan
b u ffer through TIP algorithm if Normal is
selected for Image Processor SCANIP, thro u g h
E r ror Diffusion algorithm if medium, or thro u g h
D M A without algorithm if PC Scan mode.
Commonly for all the three modes, it is pro c e s s e d
after shading correction and gamma corre c t i o n .
5
×
5 Window Processing begins after data is store d
in 32K Byte external SRAM.
Image Processor SCANIPhas the following
s p e c i f i c a t i o n s :
➀
Package: 128 Pin QFP
➁
Operating Frequency: 25 - 40MHz
➂
Minimum Scan Line Time: 1.5mS
➃
Scan Resolution: Max. 300DPI
➄
Scan Width: B4
➅
Major functions
– Internal 8bit A D C
– Black/White shading correction for each color
R . G . B
– Gamma correction for each color R.G.B
– Mono CIS (Canon, Dyna) interface
– Color CIS (Canon, Dyna, Toshiba) interface
– Automatic Motor Contro l
– Image Processing Mode : TIP, Ord e red dither,
E r ror diff u s i o n
– 256 Gray Scale
– AGC function
– PC Gray Scan function
➆
External SRAM: 32Kbyte, 15Ns Access Ti m e
3) CIS LED Driver: LED in CIS is on with 11 . 7 5 V. TR
c i rcuit is built in to drive this LED.
– Maximum LED current: 300mA
4) PC Scan function
– Resolution(V
×
H) : 3 0 0
×
3 0 0 / 7 5
×
75dpi
( P re-scanning mode)
1 9 6
×
2 0 3 / 9 8
×
2 0 3 d p i
– Mono Bit Depth : 8bits Gray Scan/1bit Te x t
Scan/1bit Halftone Scan
– Color Bit Depth : 24bits (8bits/R.G.B.)
– PC Interface: IEEE 1284 NIBBLE, BYTE, ECP
– T WAIN Driver: 1CD-ROM title provided along
with Bundle S/W.
5) Additional Spec.
– Scan Line Time : 2.5mS/line
– Contrast Control : 3 Step
( N o r m a l / D a r k e n / L i g h t e n )
– Enlargement & Reduction : 25 ~ 200%